Metallurgical composition



United States Patent M 3,087,812 METALLURGICAL COMPOSITION Joseph H. Doss, 13417 Promenade Ave., Detroit 13, Mich. No Drawing. Filed May 11, 1960, Ser. No. 28,196 1 Claim. (Cl. 75-171) The present invention relates to new and novel high temperature heat and stress resistant nickel base alloys suitable for use at extremely elevated temperatures under substantial tensile stresses and under great pressures as in the power plant units of gas turbine engines, turbojet engines, high pressure rotors as in steam power plants and similar uses.

The art of metallurgical composition with respect to the uses cited and other similar uses involving high temperatures and great stresses has been faced in the recent past with the tendency to operate at higher and higher speeds, higher pressures and higher temperatures up to 2200 F., and above. Satisfactory service life has been obtained only with cobalt base alloys within the temperature range cited and even here the technologies have been limited by the materials available.

An object of this invention is to provide alloys suitable for use at these high temperatures and stresses, in temperatures to at least 2200 F. Another object of this invention is to provide these alloys and in addition and at one and the same time provide satisfactory, which may be equated with exceptional, resistance to oxidation, even in the presence of oxidizing atmospheres such as those obtained in the operation of jet aircratt and coal-burning gas turbines.

Another object of the invention is to provide these alloys for use at high temperatures and stresses, along with the oxidation resistance, and at the same time provide these alloys possessing a low coeflicient of thermal conductivity.

Another object of the invention is to provide these alloys for use at high temperautres and stresses, resistant to oxidation, having low thermal conductivity, and also possessing freedom from temperature sink.

My experiments prove that the foregoing objects are obtained, with the provision of the highly superior properties called for, properties which possessed to the degree found in the present invention are unique, by mixing a metallurgical alloy composed of the following components, the components thereof being present in the precise proportions stated below:

1 Not to exceed.

Having compounded the metal as shown above, it was tested by an independent laboratory according to procedures substantially in conformity with the general prac- Patented Apr. 30, 1963 2 tice used by those skilled in the art of testing stainless steel and other metals for oxidation at elevated temperatures, and was found to have the following properties with respect to resistance to oxidation.

Change in weight,

Test temperature, F.: gms./cm. /hr.

1800 +0.00025 2000 +0.000Sl 2200 -0-.0O815 Test temperature, F.: Tensile strength, p.s.i.

No standard test is provided for the determination of thermal conductivity and therefore a test was devised by me for this determination, which upon calibration indica-tes a thermal coefiicient of 6 B.T.U./hr./ft. F./it., at a metal temperature of approximately 2200 F.

Upon examination it was found that the alloy engages in thermionic electron emission to a high degree and that untreated, without the use of impregnation, oxide covering or activation, has an emission of l ampere per square centimeter at a temperature of 2000" F.) The above is without the addition of thorium. Experimentally, it has been found that the addition of up to 5% thorium in powdered form or master alloy to the mix during the process of mixing the alloy has no adverse elfect upon the high temperature and stress properties of the alloy. In practice I believe that the addition of one-half of one percent is suflicient to beneficiate the emission properties of the metal by an approximate factor of 2.

I claim:

A high temperature heat and stress resistant alloy containing only the following elemental substances in proportions described by percentages by weight: Nickel, 51.8% to 59.4%; chromium, 5.92% to 10.75%; colbalt, 12.67% to 19.46%; tungsten, 5.12% to 11.2%; aluminum, 3.22% to 7.2%; molybdenum, 3.2% to 6.4%; cclumbium, not to exceed 2%; titanium, .245 to .687%; beryllium, .07% to .l9%; boron, .005% to 08%; and carbon, not to exceed .5 provided that no component listed shall account for less or more than the listed percentage of the finished alloy.

References Cited in the file of this patent UNITED STATES PATENTS 2,245,366 Rohn et al June 10, 194-1 2,246,078 Rohn et al June 17, 1941 2,912,323 Bieber Nov. 10, 1959 2,920,956 Nisbet et a1. Ian. 12, 1960 FOREIGN PATENTS 534,855 Canada Dec. 25, 1956 1,160,309 France Feb. 24, 1958 

